In this article the author talks about the incredible win by Michigan over Illinois. This article is relevant to physics because when one of the players being to move and run across the field they do not stop moving or running until another force, or the defense from the other team stop them from scoring a touchdown. The reaction time that it takes a player to see the defensive tackle is crucial also because the faster his reaction time then the faster he can avoid the tackle so he can gain more yards and eventually score. Physics is present in everything that we do on a daily basis but it the basics for all sports.
I see a bunch of kids just playing around and kicking a soccer ball of all different sizes and the balls are each moving at different speeds because of the person or animal that is kicking the ball and starting the momentum
What do you think?
How do figure skaters keep moving across the ice at high speeds for long times while seeming to expend no effort?
After the skaters gains enough momentum all they need is balance to glide across the ice so there really isn't a necessary effort after they have already reached a fast speed
Why does a soccer ball continue to roll across the field after it has been kicked?
The ball also still have momentum after the person kicks it so that it will only stop moving after there is no more momentum left.
Investigate:
In this Investigate, you will use a track and a ball to explore the question, “When a ball is released to roll down track and up the opposite side of the track, how does the vertical height that the ball reaches on the opposite side of the track relate to the vertical height from which the ball is released?”
Make a hypothesis. Answer the question to the best of your ability at this time. If the skater is released from one vertical height then it will reach the other vertical high on the opposite side of the track.
Set up the simulation and run the first trial.
Press pause to stop the simulation. Note that the simulation ignores friction effects entirely.
Check the box marked “Measuring Tape”.
Use the default track and all other default settings. Use the measuring tape to measure the initial height. 5.05 m
Press Play.
Place your cursor at the height point that the skater reaches on the opposite track. Measure the vertical height of this mark. 5.05 m
Change the position of the last blue circle to decrease the slope of the opposite track, but make sure that its end it still at least as high as the first blue circle.
Predict where the skater will reach his highest position if he begins at the same place as before. We think that they will still reach to 5.05 meters
Explain why you think so. We think so because they are both starting in the same place
Press play. (Note: if at any time you need to zoom out, because you can’t see the end of your track, click the magnifying glass with the minus sign. The screen will adjust to fit your track.)
How close was your prediction to the actual outcome? Why do you think your prediction was “close” or “way off”? Our prediction was correct his height was the same as it was before even without making the slope smaller
Measure the vertical height where the ball stopped. Write a sentence that fully describes the movement of the ball in terms of its starting and recovered vertical heights. They're all the same because wherever the ball drops it will reach the same high on the opposite side.
Repeat Steps 2 and 3, creating an even less steep slope.
First record your prediction. His height will remain equal to where he is dropped.
Compare your prediction with the outcome. The height where the ball landed and started were the same on each side because the less steep the slope on the right side the more steep the slope on the left side which helps it gain momentum.
Imagine what would happen if you changed the right-hand section of the track so that it would be horizontal (zero slope).
No matter how far along the horizontal track the skater rolls, would he ever recover his starting height? The ball would just roll right off because there is nothing to stop it
How far do you think the skater would roll? Too far for us to see on the screen
What would keep the skater rolling on a horizontal track? Momentum
Try this on the simulation. What happens? It happens the way that I predicted, the ball rolls off the slope and off the screen
Conclusion Questions:
What happens to the length of the opposite track the skater rides as the slope decreases? The length is increasing
What happens to the final vertical position on the opposite track the skater rides as the slope decreases? They still remain equal to the initial height
Remember that we are ignoring friction. The initial question was: “When a ball is released to roll down track and up the opposite side of the track, how does the vertical height that the ball reaches on the opposite side of the track relate to the vertical height from which the ball is released?” What is your answer to this question? They are always the same unless there is 0 or no slope on the opposite side of the ramp.
If the opposite track was infinitely long, and frictionless, when would the skater stop? Never, unless another force acts upon the skater
Physics Talk
Galileo's Law of Inertia-
Inertia-
the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line
moving objects will continue to move infinitely in a given direction unless a push or a pull acts on it
Newton's First Law of Motion-
an object at rest remains at rest, and an object already in motion will remain in motion with constant speed in a straight line path
an object's mass is a measure of its inertia
if it has a greater mass it will have a greater inertia
Unit of measure for mass-
kilogram
Frame of reference-
the point in which the position and or motion of an object is described from
Checking Up Questions
1.
The natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line
2.
An object at rest will remain at rest and an object in motion will remain in motion at a constant speed in a straight line path
3.
A force of some sort will need to act upon and object to stop it from moving or to slow it down
4.
Friction
5.
As the mass grows so does the inertia
6.
It determines the speed of the ball
Physics to Go
1.
It would never stop rolling if there were no friction
It would move in the same direction at the same speed unless something acted against it which is stated in Newton's first law of motion
2.
They're equal so 20 cm
3.
Nope unless you are in space where there is no friction
4.
Only if another force acts upon the puck such as it hitting the wall or something then the motion would changed which is stated in Newton's first law of motion
5.
4.5 + 2.5
7 m/s
6.
10.3 + 4.2
14.5 m/s
7.
5.6 + 2.4 = 8 m/s
5.6 - 2.4 = 3.2 m/s
square of 5.6^2 + 2.4^2
v = 6.1 m/s
tangent 0 = 2.4 / 5.6
tangent = 67
6.1 m/s
8.
67 m/s (^^^ work shown up there)
9.
15 cm / sign 45
21.2 cm
15 cm / sign 20
43.9 cm
15 cm / sign 15
58 cm
15 cm / sign 5
172 cm
10.
I think that this is all very relevant when talking about tennis. First one person starts off by hitting the ball with a racket then the other person will stop the motion of the ball by hitting it with their racket which changes the motion of where the ball is going towards the server. This all just proves Newtons first law of motion and how an object at rest will remain at rest and an object in motion will remain in motion at a constant speed in a straight line path.
What Do You Think Now?
Inertia can keep an object moving if it was already set in motion by something else, this object will then just remain in motion until any other force acts upon it and then the motion, even if insignificant, will be altered. This can happen with any object and not just a puck, or a soccer ball, or a football. If there is no friction then it will continue to move forever although that can't happen on earth because there is friction everywhere.
Section 2
What do you see?
On the top i see a boy just who is walking at a constant pace to follow an animal who is also moving at a constant pace. He's walking slow and day dreaming and as you can see there is a snail which means you are going extremely slow. On the bottom the boy is running at a constant speed to chase the animal that is in front of him. There is a heart in the speech bubble to represent he's running after something that he loves.
What do you think?
In one hour the baseball will cover 100 miles and in one second the baseball will only cover 45 meters so they are the same units of measure but one is just in a smaller fraction then the other.
Physics Talk
Calculating average speed
average speed= distance traveled / time elapsed
Calculating acceleration
acceleration = change in speed / time interval
Units of acceleration
meters per second squared
Checking Up Questions
1.
Constant distance between all of the dots and no change
Slowly the dots become further and further apart
Slowly the dots become closer and closer to each other
2.
400 m
50 s
400/50 = 8
8 = average speed
3.
Instantaneous speed is the speedometer reading at any single point during a trip and average speed is the average of your speed throughout the whole trip
4.
0 km/h
to 100 km/h
10 s
Change in speed/ over time = acceleration
100 km/h / 10 = 10
10 = acceleration
Physics To Go
1.
The speed at one specific moment is Instantaneous speed and average speed is distance/time
This was the average of the speed, not the instantaneous speed, so no.
10.
It would start out long and loose then get tight and smaller.
11.
V = d/t
V = 4/1
V = 4 m/s
V= d/t
V = 4/2
V = 2 m/s
V = d/t
V = 4/3
V = 1.3 m/s
V = d/t
V = 4/4
V= 1 m/s
V = d/t
V = 4/5
V = .8 m/s
14.
Running a Mile
Sprinting
Wrestler
Pitching
Stopping during a race
Active Physics Plus
What do you think now?
Inertia allows and object to move across a surface, if there is no friction then the object will move in the same speed and direction until it is stopped by another object. When a figure skater first begins to skate they have to push off of the ice, cause friction, and then after they begin to move then they will glide across the rest of the ice. The ice on a rink possesses very little friction which further proves these laws of motion. The ball moving across a field is basically the same thing, after it is kicked it will continue moving at a constant speed in a constant direction unless something else acts upon it.
Section 3
What do you see? What do you think?
I see a boy running pushing a ball with a stick and when he speeds up then he starts moving slower because it's harder to push the ball. The more mass the more the effect on the speed and the friction that the ball has.
Physics Talk
Newton's Second Law of Mass
Acceleration = force / mass
A - acceleration
F - force in newtons
Newton is a force needed for 1 kg of mass to accelerate
1 kg x m/s^2 = one newton
m - mass (kg)
Accelerations are caused by unbalanced forces
Small mass= Large Acceleration
Large mass= Small Acceleration
Gravity is an unbalanced force acting on an object's mass in an acceleration
Weight is the force of gravity acting on an object
Weight is calculated by w=mg
G= 9.8 m/s always
A force acting on an object causes it to accelerate
More than one force acting on an object determine the direction and motion
Net force is the sum of all of the forces
When they move in the same direction they create a larger acceleration
When they move if different directions they create zero acceleration
Checking Up Questions
1.
Accelerations are caused by unbalanced forces.
2.
Increasing an objects mass would make it's acceleration decrease.
3.
The amount of mass the object has is the same amount that it needs to accelerate.
4.
More acceleration requires heavier weight because the gravity increases as does the mass.
Physics to Go
1.
F= m(a)
F =70(5)
F = 350 N
F = m(a)
800 N = m(10)
m = 80 kg
F = m(a)
70 N = 7(a)
a = 10 kg
F = m(a)
400 N = m(5)
m = 80 kg
F = m(a)
-1500 N = 100(a)
a = -15 m/s^2
F = m(a)
F = 100(-30)
F = -3000 N
3.
a = f/m
a= 42/0.30
a = 140 m/s^2
4.
F = m(a)
F = .040(20)
F = 0.8 N
5.
The bowling ball would be harder to stop than the baseball because the bowling ball has greater mass than the baseball.
The force needed to stop a bowling ball or start it from moving would be smaller than a baseball because the acceletion for a large mass is small and the acceleration for a small mass is large.
9.
It would still be applied to the ball until the ball stopped moving.
10.
90 N
11.
800 Newtons
12.
a = F/m
a = 125?0.7
a = 179 m/s^2
13.
R = the square root of 50^2 + 120^2
R = 130 N at 67 deg. NE
14.
R = the square root of 4000^2 + 5000^2
R = 6403 N at 39 deg.
15.
F = m(a)
F = 12.8(9.8)
F = 125 N
16.
the square root of 30^2 N + 40^2 N
F = 50 N at 53 degrees
a = f/m
a = 50/5.6
a = 8.9 m/s^2
17.
the square root of 30^2 N + 20^2 N = 36 N at 34 deg.
a = f/m
a = 36/100
a = 0.36 m/s^2
a = 50/100
a = 0.5 m/s^2
18.
If the pitcher throws the .14 kg baseball at 276 m/s^2 then he ball will be pitched with a force of 38.6 N
Physics Plus
1.
125 m/s at 45 deg. NW
The square root of 5^2 + 125^2 = C^2
125(c)
tan -1 (125/125) = 45 deg.
2.
0 deg. N
the square root of 70^2 + 40^2 = c^2
81 deg. N
Northwest
What do you think now?
Throughout this section i have learned that a force is what causes and object to move. When the object is small the acceleration is large and when the object is large the acceleration is then small and all about Newtons second law of mass.
Section 4
What do you think?
Force, angle, height, and speed effect the direction and speed that an object travels.
Physics Talk
Projectile is an object traveling in the air
Affected by gravity
Trajectory is the path of the projectile
x and y components are always independent
x only affect x
y only affect y
vertical velocity effects vertical distance which is y
horizontal velocity effects horizontal distance which is x
Hang time is the time it takes for the object to reach the ground
It's also the same amount of time it takes to drop
Acceleration due to gravity is always = -9.8 m/s^2
Horizontal velocity never changes
Y = is 0 at max height
Checking Up
1.
They'll fall at the same time because they both are dropped at the same time
2.
Increase by 10 m/s
3.
Max height is 0 and the acceleration is -9.8 m/s^2
Physics to Go
7.
A and B would hit at the same time because they both have equal times that they will hit the object
8.
the square root of 2^2 + 3^2
3.6 m/s
9.
x=15cos[37]
12 m/s
d = rt
d = 12(2)
24 m
10.
y = vi + at
y = 12sin[45]
8.4 m/s
d = rt
d = 8.4(.5)
4.2 m
11.
The softball releases the softball from her glove as she pitches underhand towards the plate at 45 m/s and then when it reaches the plate the batter swings at first and then misses. The next pitch is pitched and then the batter swings hard and hits the ball straight towards the short stop at a 20 degree angle.
Homework: www.youtube.com/watch?v=1v98gDvI9i8
1.
As the girl dismounts off of the uneven bars the speed that she is going and the angle that she is going to release her hands from the bar all effect where she will land on the mat and if she will stick her landing.
2.
This plays a large part in the sport because if you don't release at the right angle and stick it perfectly then it can negatively effect your score which will determine your placement later in the competition.
Active Physics Plus
What do you think now?
I think that by recognizing that when two objects fall off something at the same time that are equal in weight they will always land at the same time brings up a very important concept. Most people when asked their opinion in the past activity said that the bullet shot would land before the bullet that was just dropped. The projectile which is the object that is moving through the air follows a trajectory, or a path that the projectile is going. The hang time is almost always the same which just continues to build off of the rest of the material that we learned in this chapter.
Section 5
What do you see and what do you think?
The girl kicked the ball and it is hitting someone in the head and then it appears to be bouncing off their head and then going into the goal that is set up. The angle and the speed that the projectile is released at effect where the ball will land and how long it will take to land. If there is a greater launch speed but at the same angle then the ball will take the same path but it will land much faster than if you launched the ball more slowly.
Physics Talk
projectile motions do not have to effect each other
there are only 2 different types of motion
constant speed along a straight line
downward acceleration
computers and graphing calculators are the methods we use to determine the motion of these projectiles
Angle, height, and speed can be altered using these methods to predict different outcomes
the slope of a projectile is always a parabola
small angles = bigger horizontal velocity; smaller vertical velocity
Downward acceleration, and Constant speed across a straight line
2.
It must "match reality in nature"
3.
As the angle increases then the height and range will increase also between 10 and 80 but at exactly 80 and 10 they both have the same range
Physics to Go
What do you think now?
When any two angles that are launched from the ground add up to make a 90 degree angle then both of those angles will have the same range. They are called complementary angles and will ALWAYS be the same for a ground to ground launch. 45 degrees will always be the highest launch point because 45 + 45 equals 90. The higher that you will launch the projectile consequently the farther it will travel in the end.
Physics Plus
Section 6
What do you see, What do you think?
There is someone sitting on a wheely chair with his feet positioned up against the wall and it appears as if he is kicking off the wall and then is pushed away from the wall with the chair.
I would tell him to start with their feet on the floor and then slowly bend their knees and push off of the floor while straightening their knees again after being in the hair. Gravity would then bring you right back down onto the floor after you're legs are straightened.
Physics Talk
Newton's 3rd Law of Motion - for every applied force there is an equal and opposite force
Forces are always equal in opposite directions
A force is always in a pair
When ever there is a motion there is an equivalent force pushing on both objects
Objects can apply force with mass and gravity
Free Body Diagram- shows the forces on an object
A person on a wheely chair is still a great example of this like the picture in "what do you see?" you can see that the force from the wall and the force of the person and both equal which then causes the chair along with the person to move after the force is applied to the wall
If the forces weren't in opposite directions then there would be too much force in one direction and it would constantly travel in that one direction
Checking Up
1
Newton's 3rd Law of Motion- for every applied force there is an equal and opposite force
2.
The earth pulls you down with gravity and you pull at the earth equally
3.
Shows forces acting on an object
Physics To Go
1.
Yes. All actions cause a equal reaction to occur
2.
No because there are springs which cause the chair to compress as you sit and then when you stand up the coils expand again like before the force was applied to them
3.
Using a spring with a needle. It is calibrated because as you stand of the scale it is also pushing up on you with springs so there are still 2 equal forces that are applied
4.
The bat would break it isn't strong enough
5.
Equal and opposite forces
Small player , smaller mass - runs faster
6.
A natural force along with no friction caused by the ice
7.
The padding used on a glove is used to protect the hand because if the ball is coming at the glove with a very powerful force then your glove is going to need to exert the same force towards the ball so that each of them are equal. This way the force is between the glove and the ball not the hand and the ball.
8.
The pitcher throws the ball towards the plate! The batter misses the ball as the runner on first steals second! The catcher then runs with the ball towards the pitchers mound to throw out the runner. The ball is thrown but since the runner is larger then the short stop who caught the ball the runner knocks over the short stop and causes him to fall backwards as the runner hits the ground.
By using deflection you can make normal forces For example while the runner slides into the base the ground is pushing up at him while he is pushing down at the ground.
What do you think now?
If you are running or jumping or even walking you apply force to the ground and that force that is on the ground is also applied right back towards your body. There are equal and opposite forces acting which makes you able to stand up straight and not fall and able the ground not to collapse. The weight is what is pushing down from your body and the normal force is acting upon you from the ground up. I also learned from the investigate that if you bend your legs and push harder on to a force you will get a harder force pushed back at you which will make you move more or father away from the wall as in the lab.
Section 7
What Do You See?
A shoe is hanging from a spring scale that is placed on ice. Since they are on ice there is no friction so the shoe can move freely with the person that is pulling it. In the other picture there is a boot on sand with a spring scale attached. It looks like the guy who is pulling the boot using the spring scale is having trouble getting it to move in the sand and is moving very slow.
What Do You Think?
Depending on what kind of shoe you wear the friction can either be less or more. If it is ice you should use an ice skate if you are on the sand you are better off wearing no shoes instead or maybe even cleats so there is more friction and you can move more quickly through the sand.
Physics Talk
The pulling force is always equal to the frictional force of an object
These forces are always equal in opposite direction
This creates a net force of 0
Normal force acts always up regarding to the surface
Weight is always acting down onto the surface
µ is the coefficient of a sliding force
µ - force of friction or the force of a normal force.
If an object begins to move then it will then continue to travel at a constant speed across a surface if the forces are equal
Checking Up
1.
They are equal because the friction force and the force of the pull are equal.
2.
It has no units because it's newtons/newtons.
3.
They are equal because the object is moving at a constant speed.
Physics to Go
1.
The shoes that are being worn play a large role in the sport that you are playing. For example if you are running outside you might want to wear cleats or running shoes so that you don't trip or fall. These cleats also help create more friction so that you can run faster and more efficiently.
2.
The ice skater would want to wear skates with smooth blades that create minimal friction so that they can have the best speed and agility. There are even rugged edges so that the skater can stop and do different tricks.
3.
No because not one court is the same as another.
4.
For each court there are different pairs of shoes that create different amounts of friction.
5.
.03 = x/600
x = 18 N
6.
w=mg
w= 1000(9.8)
w= 9800 N
µ= f/n
.55= f/9800
f= 5390 N
f= ma
-5390=1000a
a= -5.39 m/s2
vf=vi +at
0= vi+-5.39(6)
vi= 32.34 m/s
The initial speed was 32.24 and it ended up being the same so he wsa spring because he was going 29 so he's going to fast and has to stop most abruptly.
7.
Air and water resistance depend on speed. The resistance is always the same on both objects.
8.
It will make it so that you can only start at a certain speed so that you do not have an advantage. If you buy shoes that have less friction on the bottom then that would work.
10.
You need friction to do everything, even walk. It keeps us safe and helps us keep blanace and control. The friction used by cleats will create friction in even rough surfaces.
11.
While running into the field Derek Jeter is striding using his long legs to catch the ball on the outskirts of the infield. The rough ground would be so hard to run on if he was not wearing his cleats with the large spikes in the bottom. They keep his feet planted in the spaces where he runs. He takes a large stride towards the ball and then throws his body onto the ground expecting to catch it yet it lets the ball drop and the runner scores and the Yankees lose the game!
Physics Plus
Bowling With Blocks
Tension (N)
Ff (N)
Total Weight (N)
µ
Class Average
% difference
.5
.5
1.4 N
.36
.325
3.5 %
class average-coefficient of friction/class average (100)
.36-.325/.325(100)
3.5%
This shows the friction over the weight in Newtons which would be between the block and the ground.
2.
They were all very similar numbers along with mine and Jesse's. It really depends on how you did the experiment because as i saw many of them vary. They are all similar but not exactly the same. You always have random and systematic errors.
3.
Mine were close but not exactly as close as I would have liked them to do. The answers were precise though for the most part. The percent errors that I had were average to the percent errors of the class.
4.
Friction is everywhere so it applies to basically everything we do everyday.
5.
If you are wrong in your calculations then they were be systematic errors but if you are experimenting then instead of systematic errors they would be experimental. If the measuring tape was not in a straight line then your calculations would be off also if you calculated the weight of the black wrong. If the weight is wrong then the time would also be wrong too.
What do you think now?
Now that we have completed the section I've learned that depending on the activity that you are doing you should change the shoes and apparel that you wear to maximize your efforts. Some sports require more friction and other require less. It would not be beneficial for someone to we're cleats while they are trying to ice skate. Most of the time you want to raise the coefficient of friction and make the sliding friction higher so you can plant your feet more steadily like in tennis, basketball, baseball, and others. One of the only ones that you would want to minimize the coefficient of friction and make the sliding friction lower would be ice skating and other sports where you want to slide.
Section 8
What do you see, what do you think?
In the picture you see that there is horizontal speed which is being used to try to transform the pole into vertical acceleration. As the pole bends it pushes off the ground allowing the girl to fly in the air in attempt to reach the top of the roof. The pole is extremely flexible so the pole can expand and then use that energy to lift the person off the ground. If the pole is only 11 meters long then there is no way he can get past a 12 meter fence because the acceleration would not be enough. The length of the pole and the momentum that is created are the factors that effect the outcome.
Investigate
1.a.) Techniques- applying force to the ruler, greater deflection
b.) Ruler Position- sticking less of the ruler out from the table, positioning the penny at the end of the ruler.
1.a.) We will be able to conclude whether or not the amount of ruler sticking out from the table affects the height of the coin.
b.) The height of the penny will be recorded.
c.) A meter stick will be used to measure.
d.) We will look at the height of the coin and compare it with the distance off the table.
Trial 1
(4cm)
Trial 2
(6cm)
Trial 3
(8cm)
50.5
97
85
56
88.5
78
53.5
81
87
Conclusion: The farther the ruler is placed off the table, the higher the penny will travel.
Physics Talk
speed and position vary depending on the strength of the force
Kinetic Energy: motion
Gravitational Potential Energy: Position
Energy Change:
Kinetic, potential energy = original kinetic, potential energy
This is the law of conservation of energy
W = f(d)
F= force in N
D= distance in m
work= the energy possessed by a spring when it is stretched or compressed
EPE: .5(k)(x)^2
K= spring in N
X= stretch in meters
GPE: mgh
M= Mass in kg
G= 9.8
H= Height in m
KE: .5(m)(v)^2
M= mass in kg
V= velocity in m's
Checking Up Questions
1.
It is required to change the energy of the object.
2.
You get it from the force that's acting on the ruler which is the EPE.
3.
He will use his kinetic energy while it is changed to the EPE
4.
Joules
Type of Energy
Description
Equation
Kinetic Energy
Energy while an object is moving
KE=1/2(m)(v)^2
Gravitational Potential Energy
Energy possessed by an object while it is above the lowest point on the graph
GPE=(m)(g)(h)
Elastic Potential Energy
Energy of a spring, due to compression
EPE=1/2(k)(x)^2
Work
Caused by a force acting over distance parallel to the direction of motion
W=(f)(d)
Physics To Go
1.
Work is required initially, and then it changes to kinetic, and then changes to GPE, which then changes to kinetic and ends with work out.
2.
Elastic potential energy to kinetic energy while swinging, and then there is work on the ball. After work on the ball, that changes to Kinetic, which changes to gravitational, and ends with work out.
3.
KE=GPE
1/2(m)(v)^2=(m)(g)(h)
1/2(m)(12)^2=m(9.8)(h)
72=9.8(h)
h = 7.3 m
4.
The limiting factor is the initial velocity, plus the work on the pole. The pushing off the pole is minor compared to initial speed.
5.
If the temperature increases, it decreases the height because some of the total energy is lost this way (when heat leaves the system).
6.
KE=GPE
1/2(m)(v^2)=(m)(9.8)(4.55)
1/2(v)^2=44.59
v = 9.5 m/s
7.
Increase
KE=GPE
1/2(v^2)=(9.8)(6.14)
10.97m/s = v
8.
GPE=KE
(2)(9.8)(100)=1/2(2)(v^2)
1960=v^2
v = 44.27 m/s
There isn't sufficient information to do the problem.
9.
W=EPEf
W=1/2kx^2
W=1/2(1500)(.25)^2
W=46.88J
EPE=KE
46.88=1/2(m)(v)^2
46.88=1/2(.1)(v)^2
v = 30.6m/s
10.
EPE=W
1/2kx^2=(f)(d)
1/2(315)(.3)^2=W
W = 14.2 J
W=(f)(d)
14.2=f(.3)
F = 47.3 N
11.
GPE=EPE
mgh=1/2(k)(x)^2
(.04)(9.8)(1)=1/2(18)(x)^2
x = .21 m
12.
F = m(a)
GPE=(m)(g)(h)
= (kg)(m/s^2)(m)
KE=1/2mv^2
1/2(kg)(m/s)^2
1kg(1m/s^2) = J
EPE = 1/2(k)(x)^2
1/2(N)(m)^2
13.
You would use epe=ke which does the work to stop him from moving
14.
You need work which then makes KE then gravitational energy
15.
You need work to make it start moving after it starts moving it then have KE and then it turns into GPE and then back to KE then W to stop it from moving.
16.
We're gonna do baseball. The pitcher is going to begin to pitch the ball at 99 mph and as it passes over the plate the batter uses work to swing the bat. The bat then hits the ball using work and the ball then repels off the bat and goes flying into right field. As the ball gets faster and faster the work used to hit the ball then becomes kinetic energy. The player in the outfield then runs towards the ball and using work pushes off the ground to dive and try to stop the ball from landing on the ground. He finally catches using work and then throws it back towards the pitcher to begin the next pitch of the game.
What do you think now?
You would have to make your speed faster because the height cannot change that quickly. If you do that then you will get more distance for a shorter amount of time also. You cannot just increase the height without also increasing the initial velocity. So by making the initial velocity higher the KE will also rise which also makes the EPE much bigger. This will make the chances of him getting to a higher height will be more likely.
Section 9
What do you see, what do you think?
There is a skater in the picture who had just leaped off of the ice and is spinning in the air. The helicopter above looks like it is measuring the amount of time that she is in the air. I don't think that is humanly possible to defy gravity because it cannot be altered depending on who you are. Gravity is ALWAYS the same no matter how good, or bad, you are at a sport. By this skater jumping high to finish her spins she is still not defying gravity she is just applying enough work that is needed for her to finish the trick that she is doing.
Investigate
Pre lab:
1.
20 frames
2/3 second
Yes, max height
1 sec
Lab:
1.
bent, to unbent knees
work, to gravitational potential energy
2.
the energy it takes to unbend your knees
the force to push off the ground, hang time, height of jump, and distance of bend in knees
the meter stick and the force platform
we can run trials where a partner will measure the height of the person, the distance they bend, and the distance they jump
My % error wasn't that far off from my actually force.
1587-1892(-1)/1587.9(100)
19.2 % error
Conclusion
This lab showed us how the transfer of energy relates to jumping. We can now infer that the more energy the higher you will jump. The more force exerted into the ground creates a greater max height.
Physics Talk
Epe is produced from using a spring, or as a person bending your knees
Gpe is produced after you use Epe, and or jump or are in motion
Ke also is produced after you using a spring and are in motion
Energy is always equal
The greater this distance the greater the epe because the gpe is based off of weight height and velocity
if you jump on a tramp it is like jumping on a spring
It already possesses Pe, and you are always moving which means you always have Ke
You start with Epe because it is on springs and then it will convert to Ke and then Gpe because eventually you have to stop moving
Checking Up
1.
When you bend your knees it gives you enough spring to create Epe
2.
You would gain Ke and Gpe and it would stop at Gpe
3.
Sound, electrical, and chemical energy
Physics To Go
1.
W=f(d)
W=(50)(9.8)(1)
W = 490 J
2.
Work begins when you push off the bobsled then it turns into Gpe which then gains Ke then ends it work when you try to stop
3.
If you watch it in slow motion then you can see that there is no hang time and you cannot defy gravity. Only the max height changes
4.
You need to prove it by doing an experiment
5.
Bend as far down as you can then jump and do it a lot slower just don't bend too low so that you have less work
6.
W=(f)(d)
1(1)= 1 J
1(10)=10 J
10(1)=10 J
.1(100)= 10 J
100(.1)= 10 J
7.
They're the same because of the law of conservation of energy
8.
They're the same because of the law of conservation of energy
9.
W=(f)(d)
W=50(43)=2150 J
10.
KE=1/2(m)(v)^2
KE=1/2(62)(8.2)^2
KE = 2,084.4 J
11.
F= (m)(a)
30=(5)(a)
a = 6 m/s^2
W=(f)(d)
W=30(18.75)
W = 562.5 J
12.
W=(f)(d)
40,000=3200(d)
d = 12.5 m
F=(m)(a)
(m=3200/9.8)
3200=(326.5)(a)
a = 9.8 m/s^2
13.
KE=W
1/2(m)(v)^2=(f)(d)
1/2)(.15)(40^2)= W
120 J = W
14.
W=KE
(f)(d) =1/2(m)(v)^2
417(d)=1/2(64)(15)^2
d = 17.3 m
15.
Ke when he runs
Epe when the pole hits the ground
Gpe when it gets to max height
Ke when its about to stop
W when it stops
KE
GPE
EPE
Sum
Running
10 J
0
0
10 J
Full Bend of pole
1 J
0
9
10 J
Peak Height
0
10 J
0
10 J
Landing
4 J
6 J
0
10 J
Cushion Collapse
0
0
0
0
16.
Gpe is at max hegiht
Ke when its about to bounce off the tramp
Epe when it hits the tramp
KE
GPE
EPE
Sum
Peak Height
0
100 J
0
100 J
Landing
10 J
40 J
50 J
100 J
Lowest height
0
0
100 J
100 J
17.
Gpe is max height
Ke is while running
W is when he stops at the bottom
KE
GPE
EPE
Sum
Top of Mountain
0
100
0
100
Middle of Mountain
50 J
50 J
0
100 J
Bottom of Mountain
100 J
0
0
100 J
18.
And Sammi Panso is up next she walks up to the batters box and looks the pitcher in the eye. She throws an extremely fast curve ball but bam! she still hits it using work. The ball going sailing into left field while gaining Ke and it's almost over the fence but it hits the wall and falls into the fielders glove where the fielder has to use work to catch it, but not in time! The runner then scores and sammi's team is up and point and they win the championship!
Physics Plus
1.
Gpe =Ke + Gpe
(m)(g)(h)=1/2(m)(v)^2 + (m)(g)(h)
(9.8)(50)=1/2(v^2) + (9.8)(30)
490=1/2(v^2) + 294
v^2=392
v = 19.8 m/s
You don't need the mass because they can all cancel out
It is not possible for an athlete to defy gravity because it is impossible. It only looks that way because when they leap into the air displacement occurs. While watching them in slow motion you can see all of the different frames where they move slightly up and down and towards the left and the right. These skaters don't defy gravity they just gain enough Ke to be able to finish their trick. This law that is used (the conservation of energy) proves this. The more Ke that the skater has the longer they can stay in the air.
http://www.nytimes.com/2010/11/07/sports/ncaafootball/07quad.html?_r=1&ref=ncaafootball
In this article the author talks about the incredible win by Michigan over Illinois. This article is relevant to physics because when one of the players being to move and run across the field they do not stop moving or running until another force, or the defense from the other team stop them from scoring a touchdown. The reaction time that it takes a player to see the defensive tackle is crucial also because the faster his reaction time then the faster he can avoid the tackle so he can gain more yards and eventually score. Physics is present in everything that we do on a daily basis but it the basics for all sports.
What do you see?
Table of Contents
What do you think?
How do figure skaters keep moving across the ice at high speeds for long times while seeming to expend no effort?
Why does a soccer ball continue to roll across the field after it has been kicked?
Investigate:
In this Investigate, you will use a track and a ball to explore the question, “When a ball is released to roll down track and up the opposite side of the track, how does the vertical height that the ball reaches on the opposite side of the track relate to the vertical height from which the ball is released?”
Make a hypothesis. Answer the question to the best of your ability at this time.
If the skater is released from one vertical height then it will reach the other vertical high on the opposite side of the track.
5.05 m
5.05 m
We think that they will still reach to 5.05 meters
We think so because they are both starting in the same place
Our prediction was correct his height was the same as it was before even without making the slope smaller
They're all the same because wherever the ball drops it will reach the same high on the opposite side.
His height will remain equal to where he is dropped.
The height where the ball landed and started were the same on each side because the less steep the slope on the right side the more steep the slope on the left side which helps it gain momentum.
The ball would just roll right off because there is nothing to stop it
Too far for us to see on the screen
Momentum
It happens the way that I predicted, the ball rolls off the slope and off the screen
The length is increasing
They still remain equal to the initial height
They are always the same unless there is 0 or no slope on the opposite side of the ramp.
Never, unless another force acts upon the skater
Physics Talk
Galileo's Law of Inertia-
Inertia-
the natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line
moving objects will continue to move infinitely in a given direction unless a push or a pull acts on it
Newton's First Law of Motion-
an object at rest remains at rest, and an object already in motion will remain in motion with constant speed in a straight line path
an object's mass is a measure of its inertia
if it has a greater mass it will have a greater inertia
Unit of measure for mass-
kilogram
Frame of reference-
the point in which the position and or motion of an object is described from
Checking Up Questions
1.
2.
3.
4.
5.
6.
Physics to Go
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
What Do You Think Now?
Inertia can keep an object moving if it was already set in motion by something else, this object will then just remain in motion until any other force acts upon it and then the motion, even if insignificant, will be altered. This can happen with any object and not just a puck, or a soccer ball, or a football. If there is no friction then it will continue to move forever although that can't happen on earth because there is friction everywhere.
Section 2
What do you see?
What do you think?
Physics Talk
Checking Up Questions
1.
2.
3.
- Instantaneous speed is the speedometer reading at any single point during a trip and average speed is the average of your speed throughout the whole trip
4.Physics To Go
1.
- The speed at one specific moment is Instantaneous speed and average speed is distance/time
2.- V = d/t
- V = 1000/15
- V = 66.7 m/s
- V = d/t
- V = 84/6
- V = 14 m/s
- V = d/t
- V = 9.6/2
- V = 4.8 km/hr
- V = d/t
- V = 400/4.5
- V = 88.9 km/hr
3.4.
6.
7.
8.
9.
10.
11.
14.
Active Physics Plus
What do you think now?
Inertia allows and object to move across a surface, if there is no friction then the object will move in the same speed and direction until it is stopped by another object. When a figure skater first begins to skate they have to push off of the ice, cause friction, and then after they begin to move then they will glide across the rest of the ice. The ice on a rink possesses very little friction which further proves these laws of motion. The ball moving across a field is basically the same thing, after it is kicked it will continue moving at a constant speed in a constant direction unless something else acts upon it.
Section 3
What do you see? What do you think?
I see a boy running pushing a ball with a stick and when he speeds up then he starts moving slower because it's harder to push the ball. The more mass the more the effect on the speed and the friction that the ball has.
Physics Talk
Checking Up Questions
1.
2.
3.
4.
Physics to Go
1.
3.
4.
5.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
Physics Plus
1.
2.
What do you think now?
Throughout this section i have learned that a force is what causes and object to move. When the object is small the acceleration is large and when the object is large the acceleration is then small and all about Newtons second law of mass.
Section 4
What do you think?
Force, angle, height, and speed effect the direction and speed that an object travels.
Physics Talk
Checking Up
1.
2.
3.
Physics to Go
7.
8.
9.
10.
11.
Homework:
www.youtube.com/watch?v=1v98gDvI9i8
1.
- As the girl dismounts off of the uneven bars the speed that she is going and the angle that she is going to release her hands from the bar all effect where she will land on the mat and if she will stick her landing.
2.Active Physics Plus
What do you think now?
I think that by recognizing that when two objects fall off something at the same time that are equal in weight they will always land at the same time brings up a very important concept. Most people when asked their opinion in the past activity said that the bullet shot would land before the bullet that was just dropped. The projectile which is the object that is moving through the air follows a trajectory, or a path that the projectile is going. The hang time is almost always the same which just continues to build off of the rest of the material that we learned in this chapter.
Section 5
What do you see and what do you think?
The girl kicked the ball and it is hitting someone in the head and then it appears to be bouncing off their head and then going into the goal that is set up. The angle and the speed that the projectile is released at effect where the ball will land and how long it will take to land. If there is a greater launch speed but at the same angle then the ball will take the same path but it will land much faster than if you launched the ball more slowly.
Physics Talk
Checking Up
1.
2.
3.
Physics to Go
What do you think now?
When any two angles that are launched from the ground add up to make a 90 degree angle then both of those angles will have the same range. They are called complementary angles and will ALWAYS be the same for a ground to ground launch. 45 degrees will always be the highest launch point because 45 + 45 equals 90. The higher that you will launch the projectile consequently the farther it will travel in the end.
Physics Plus
Section 6
What do you see, What do you think?
Physics Talk
Checking Up
1
2.
3.
Physics To Go
1.
- Yes. All actions cause a equal reaction to occur
2.- No because there are springs which cause the chair to compress as you sit and then when you stand up the coils expand again like before the force was applied to them
3.- Using a spring with a needle. It is calibrated because as you stand of the scale it is also pushing up on you with springs so there are still 2 equal forces that are applied
4.- The bat would break it isn't strong enough
5.- Equal and opposite forces
- Small player , smaller mass - runs faster
6.- A natural force along with no friction caused by the ice
7.- The padding used on a glove is used to protect the hand because if the ball is coming at the glove with a very powerful force then your glove is going to need to exert the same force towards the ball so that each of them are equal. This way the force is between the glove and the ball not the hand and the ball.
8.What do you think now?
Section 7
What Do You See?
A shoe is hanging from a spring scale that is placed on ice. Since they are on ice there is no friction so the shoe can move freely with the person that is pulling it. In the other picture there is a boot on sand with a spring scale attached. It looks like the guy who is pulling the boot using the spring scale is having trouble getting it to move in the sand and is moving very slow.
What Do You Think?
Depending on what kind of shoe you wear the friction can either be less or more. If it is ice you should use an ice skate if you are on the sand you are better off wearing no shoes instead or maybe even cleats so there is more friction and you can move more quickly through the sand.
Physics Talk
Checking Up
1.
- They are equal because the friction force and the force of the pull are equal.
2.- It has no units because it's newtons/newtons.
3.Physics to Go
1.
- The shoes that are being worn play a large role in the sport that you are playing. For example if you are running outside you might want to wear cleats or running shoes so that you don't trip or fall. These cleats also help create more friction so that you can run faster and more efficiently.
2.- The ice skater would want to wear skates with smooth blades that create minimal friction so that they can have the best speed and agility. There are even rugged edges so that the skater can stop and do different tricks.
3.- No because not one court is the same as another.
4.- For each court there are different pairs of shoes that create different amounts of friction.
5.- .03 = x/600
- x = 18 N
6.- w=mg
- w= 1000(9.8)
- w= 9800 N
- µ= f/n
- .55= f/9800
- f= 5390 N
- f= ma
- -5390=1000a
- a= -5.39 m/s2
- vf=vi +at
- 0= vi+-5.39(6)
- vi= 32.34 m/s
- The initial speed was 32.24 and it ended up being the same so he wsa spring because he was going 29 so he's going to fast and has to stop most abruptly.
7.- Air and water resistance depend on speed. The resistance is always the same on both objects.
8.- It will make it so that you can only start at a certain speed so that you do not have an advantage. If you buy shoes that have less friction on the bottom then that would work.
10.- You need friction to do everything, even walk. It keeps us safe and helps us keep blanace and control. The friction used by cleats will create friction in even rough surfaces.
11.Physics Plus
Bowling With Blocks
.36-.325/.325(100)
3.5%
Acceleration:
µ= f/n
.36= f/1.4
F= -.504
-.504= .18477a
a= -.3666
Velocity:
vf= vi + at
0=vi+ -.36 (2.06)
Vi= .7416
0= vi+(-.36) (2.00)
vi= .72
0= vi + (-.36)(1.72)
vi= .6192
calculated time:
Vf= Vi + at
.7416 + (-.36)t
t= 2.78
.72+ (-.36)t
t= 2.99
.6192 + (-.36)t
t= 1.99
Error:
Calculated - Measured / calculated (100) = percent error
Discussion Questions
1.
- This shows the friction over the weight in Newtons which would be between the block and the ground.
2.- They were all very similar numbers along with mine and Jesse's. It really depends on how you did the experiment because as i saw many of them vary. They are all similar but not exactly the same. You always have random and systematic errors.
3.- Mine were close but not exactly as close as I would have liked them to do. The answers were precise though for the most part. The percent errors that I had were average to the percent errors of the class.
4.- Friction is everywhere so it applies to basically everything we do everyday.
5.What do you think now?
Now that we have completed the section I've learned that depending on the activity that you are doing you should change the shoes and apparel that you wear to maximize your efforts. Some sports require more friction and other require less. It would not be beneficial for someone to we're cleats while they are trying to ice skate. Most of the time you want to raise the coefficient of friction and make the sliding friction higher so you can plant your feet more steadily like in tennis, basketball, baseball, and others. One of the only ones that you would want to minimize the coefficient of friction and make the sliding friction lower would be ice skating and other sports where you want to slide.
Section 8
What do you see, what do you think?
In the picture you see that there is horizontal speed which is being used to try to transform the pole into vertical acceleration. As the pole bends it pushes off the ground allowing the girl to fly in the air in attempt to reach the top of the roof. The pole is extremely flexible so the pole can expand and then use that energy to lift the person off the ground. If the pole is only 11 meters long then there is no way he can get past a 12 meter fence because the acceleration would not be enough. The length of the pole and the momentum that is created are the factors that effect the outcome.
Investigate
1.a.) Techniques- applying force to the ruler, greater deflection
b.) Ruler Position- sticking less of the ruler out from the table, positioning the penny at the end of the ruler.
1.a.) We will be able to conclude whether or not the amount of ruler sticking out from the table affects the height of the coin.
b.) The height of the penny will be recorded.
c.) A meter stick will be used to measure.
d.) We will look at the height of the coin and compare it with the distance off the table.
(4cm)
(6cm)
(8cm)
Conclusion: The farther the ruler is placed off the table, the higher the penny will travel.
Physics Talk
Checking Up Questions
1.
- It is required to change the energy of the object.
2.- You get it from the force that's acting on the ruler which is the EPE.
3.- He will use his kinetic energy while it is changed to the EPE
4.1.
- Work is required initially, and then it changes to kinetic, and then changes to GPE, which then changes to kinetic and ends with work out.
2.- Elastic potential energy to kinetic energy while swinging, and then there is work on the ball. After work on the ball, that changes to Kinetic, which changes to gravitational, and ends with work out.
3.- KE=GPE
- 1/2(m)(v)^2=(m)(g)(h)
- 1/2(m)(12)^2=m(9.8)(h)
- 72=9.8(h)
- h = 7.3 m
4.- The limiting factor is the initial velocity, plus the work on the pole. The pushing off the pole is minor compared to initial speed.
5.6.
7.
8.
9.
10.
11.
12.
- F = m(a)
- GPE=(m)(g)(h)
- = (kg)(m/s^2)(m)
- KE=1/2mv^2
- 1/2(kg)(m/s)^2
- 1kg(1m/s^2) = J
- EPE = 1/2(k)(x)^2
- 1/2(N)(m)^2
13.- You would use epe=ke which does the work to stop him from moving
14.- You need work which then makes KE then gravitational energy
15.- You need work to make it start moving after it starts moving it then have KE and then it turns into GPE and then back to KE then W to stop it from moving.
16.What do you think now?
You would have to make your speed faster because the height cannot change that quickly. If you do that then you will get more distance for a shorter amount of time also. You cannot just increase the height without also increasing the initial velocity. So by making the initial velocity higher the KE will also rise which also makes the EPE much bigger. This will make the chances of him getting to a higher height will be more likely.
Section 9
What do you see, what do you think?
There is a skater in the picture who had just leaped off of the ice and is spinning in the air. The helicopter above looks like it is measuring the amount of time that she is in the air. I don't think that is humanly possible to defy gravity because it cannot be altered depending on who you are. Gravity is ALWAYS the same no matter how good, or bad, you are at a sport. By this skater jumping high to finish her spins she is still not defying gravity she is just applying enough work that is needed for her to finish the trick that she is doing.
Investigate
Pre lab:
1.
Lab:
1.
- bent, to unbent knees
- work, to gravitational potential energy
2.- the energy it takes to unbend your knees
- the force to push off the ground, hang time, height of jump, and distance of bend in knees
- the meter stick and the force platform
- we can run trials where a partner will measure the height of the person, the distance they bend, and the distance they jump
3.- || My height(m) || Bend(m) || Height jumped(m) || Mass(kg) ||
- W=GPE
- (F)(d) = (m)(g)(h)
- .32(F) = (50.34)(9.8)(1.03)
- F = 1,587.9 N
4.|| 1.56 || 0.32 || 0.48 || 50.34 ||
- On the platform when i jumped i got 1,892 N
5.Conclusion
Physics Talk
Checking Up
1.
- When you bend your knees it gives you enough spring to create Epe
2.- You would gain Ke and Gpe and it would stop at Gpe
3.Physics To Go
1.
- W=f(d)
- W=(50)(9.8)(1)
- W = 490 J
2.- Work begins when you push off the bobsled then it turns into Gpe which then gains Ke then ends it work when you try to stop
3.- If you watch it in slow motion then you can see that there is no hang time and you cannot defy gravity. Only the max height changes
4.- You need to prove it by doing an experiment
5.- Bend as far down as you can then jump and do it a lot slower just don't bend too low so that you have less work
6.- W=(f)(d)
- 1(1)= 1 J
- 1(10)=10 J
- 10(1)=10 J
- .1(100)= 10 J
- 100(.1)= 10 J
7.- They're the same because of the law of conservation of energy
8.- They're the same because of the law of conservation of energy
9.10.
11.
12.
13.
14.
15.
16.
17.
18.
Physics Plus
1.
- Gpe =Ke + Gpe
- (m)(g)(h)=1/2(m)(v)^2 + (m)(g)(h)
- (9.8)(50)=1/2(v^2) + (9.8)(30)
- 490=1/2(v^2) + 294
- v^2=392
- v = 19.8 m/s
- You don't need the mass because they can all cancel out
2.3.
What do you think now?
It is not possible for an athlete to defy gravity because it is impossible. It only looks that way because when they leap into the air displacement occurs. While watching them in slow motion you can see all of the different frames where they move slightly up and down and towards the left and the right. These skaters don't defy gravity they just gain enough Ke to be able to finish their trick. This law that is used (the conservation of energy) proves this. The more Ke that the skater has the longer they can stay in the air.